In the manufacture of glass articles, it is common to provide a glass forehearth and multiple orifices which are controlled by reciprocable needles or plungers in order to provide the necessary uniform weight of gobs. Plural needles and orifices are utilized in order to maximize glass production.
Typical systems are shown in U.S. Pat. Nos. 1,529,948, 1,792,932, 1,926,764, 3,711,266, 4,478,631, 4,554,000, 4,581,054 and 4,793,849.
In such systems it is common to manually adjust each plunger. Furthermore in such systems, the operating mechanisms are often in overlying relationship to the plungers and therefore are subject to extreme heat conditions and contaminants of oil or metal that can jeopardize the purity of the molten glass.
Accordingly among the objectives of the present invention are to provide a multiple orifice glass system wherein each plunger is individually mounted in association with its respective servo-motor; wherein each servo control can be automatically controlled to produce an accurate weight gob during operation; wherein the actuating servo mechanisms are mounted on the side of the forehearth and cannot contaminate the glass and are protected from the heat of the glass; wherein the individual weight of the plunger and support arms is counterbalanced by an air spring; and wherein a single plunger can be consulted, operated and controlled individually.
In accordance with the invention a multiple orifice glass feed system for use with a glass forehearth including a plurality of closely spaced plungers, each of which is individually supported independently of the other. Each plunger includes a servo controlled linear actuator motor and an arm extending between each plunger and its respective servo-motor. Each servo-motor has an axis parallel to the associated axis of the plunger. An air spring is associated with each plunger for balancing the weight of each plunger and its respective arm. The center lines of the plungers lie generally in a plane. Unlike the prior commercial practices which confine the arms to a straight line between the orifice and the motor or actuator, at least some of the arms of the present invention take circuitous routes incorporating parallel and angular portions. A feedback system is provided to monitor the position of each individual needle independently of the others at all times and make corrections to the actual position of the needle if desired.
In one form the center lines of the major portions of the arms are parallel to the plane of the plungers. In another form the center lines of the major portions of the arms are perpendicular to the plane of the plungers. Although the system is especially applicable to a plurality of plungers and is shown as applied to four plungers, it is applicable to a lesser number of plungers or a single plunger.
In another form, each servo-motor is part of a module and moves a movable frame for vertical movement on spaced vertical shafts. Each movable frame supports a plunger arm. The modules are mounted in side by side relationship with one another.
Each assembly of an arm and servo controlled linear actuator motor is preferably provided in an elongated rectangular module such that a plurality of modules can be provided in closely spaced relationship at one side of a forehearth.